The present invention relates generally to a method and apparatus of attaching a downhole member to a cased wellbore and more particularly, to attaching a tool downhole within a cased wellbore.
As a hydrocarbon well is drilled, the bore hole is lined with a steel pipe known as casing. This casing is cemented to an outer casing or the surrounding earth formation and provides a strong, continuous lining of the sides of the borehole. A wide variety of downhole tools may be affixed to the inside of the casing for conducting a well operation as for example well reference members, pipe hangers, anchors, and packers. The connection of the tool to the inside of the casing is used to support pipe or other member within the casing, to pack off the flow bore of the casing, to anchor a well tool for conducting a well operation, or to resist forces produced by wellbore pressure, drilling operations, milling and sidetracking operations, or other downhole well operations and processes.
Typically downhole members are affixed to the inside of the casing by slips. Slips are normally made from a hardened material and are reciprocably supported in windows in a downhole member. The slips engage the casing through teeth on the outside of the slip. The inside of the slip normally has a tapered surface which interfaces with another tapered surface located on a cone member. When run into the wellbore, the slip is positioned outside of the cone with little or no engagement between the tapered surfaces. When the downhole member is set in place, the cone moves toward the slip forcing the tapered surfaces together. The interfacing tapered surfaces cam the slip outwardly into engagement with the wall of the casing. The cone remains in place behind the slip to maintain the engagement between the slip and the casing wall.
The cone and the slip are normally located on the outside of a central tubular body that often includes an open bore extending through the downhole member. The stacked location of the slip, cone, and body decrease and restrict the diameter of the flowbore through the casing. It is often advantageous to maximize the through bore in the downhole member in order to facilitate operations in the casing below the set downhole member. Many designs have been developed to maximize the through bore using the traditional cone and slip system. These designs often involved making the slips, cones, and body as thin as possible. These designs reach a limit in maximizing the through bore due to the pressures and loads which must be withstood by the downhole member.
The present invention overcomes these and other limitations of the prior art.